1. Field of the Invention
The present invention relates to a welding wire capable of forming a weld having high strength at elevated temperatures as well as high crack resistance, and a welding method using the welding wire.
2. Description of the Related Art
When welding such as butt welding or fillet welding is performed, hot cracking occasionally occurs during the welding due to coarsening of crystal grains of the weld metal. Thus, attempts have hitherto been made to reduce the size of crystal grains of welds.
For example, Unexamined Japanese Patent Publication No. H5-138394 proposes a method wherein Ti is added to welding wire so that minute TiN particles may be produced and dispersed in the weld during welding, to allow minute crystal grains of weld metal to be formed around the TiN particles as nuclei.
Also, Unexamined Japanese Patent Publication No. H9-225680 proposes a method in which suitable amounts of Al and Mg are added to welding wire so that the crystal grains of the weld may be equiaxed and reduced in size.
Recently, however, higher weld crack resistance and increased strength at elevated temperatures are required, and the above conventional techniques do not satisfactorily meet the requirements.